Minimizing Energy for Wireless Web Access Using Bounded Slowdown

On many battery-powered mobile computing devices, the wireless network
is a significant contributor to the total energy consumed during its
operation. In this paper, we investigate the interaction between
energy-saving protocols and TCP performance for Web-like transfers.
We show that static protocols like the popular IEEE 802.11
power-saving mode (PSM) can harm performance by increasing fast round
trip times (RTTs) to 100ms, and that under typical Web
browsing workloads, current implementations will unnecessarily spend
energy waking up during long idle periods.

To overcome these problems, we present a power-saving scheme that
dynamically adapts to network activity called the Bounded-Slowdown
(BSD) protocol . The BSD protocol is an optimal solution to the
problem of minimizing energy consumption while guaranteeing that a
connection's RTT does not increase by more than a factor p over
its base RTT, where p is a protocol parameter that exposes the
trade-off between minimizing energy and reducing latency. We present
several trace-driven simulation results that show that, compared to
802.11 PSM, the Bounded-Slowdown protocol reduces average Web page
retrieval times by 5-64%, while simultaneously reducing energy
consumption by 1-14% (and by 13X compared to no power management).